Startup plans Linux-based PLC

PARK RIDGE, Ill.  Acting on Web-site feedback from automation engineers, startup Control.com Inc. has announced plans to do what no industrial supplier has dared before  develop a Linux-based programmable logic controller.

The concept behind the company's plan, known as the Puffin PLC project, is to create a "soft PLC," a PC-based control system that incorporates the ladder logic and flowcharting abilities of conventional PLCs. Like all PLCs, the system would be used to control industrial processes.

Control.com (Hopkinton, Mass.) will support development of free, open source code for the controller, which will be introduced during the coming year. The creators of the source code will be 150 unpaid volunteers from the "Automation List"  a catalog of more than 3,000 automation engineers that was started by the company's president, Ken Crater, in 1994.

Open source code

Unlike conventional PLCs, the Puffin PLC would give automation engineers access to free and open source code, which will be layered atop a Linux-based operating system. Although PC-based industrial control software is already available from companies like Steeplechase Software (Ann Arbor, Mich.) and Think & Do Software (Ann Arbor), such software is typically based on Windows NT or Windows 2000 operating systems, which are not considered open to users.

"In industrial automation, this is the first time that users have designed a control that's going to be free to all other users of PLCs," said Tom Bullock, president of Industrial Controls Consulting (Fond du Lac, Wis.), a company that specializes in industrial controls marketing issues.

In a historical sense, the use of open source code is a dramatic departure for the PLC market. PLCs were introduced in 1970 as electrical relay replacers for industrial automation applications. Since then, they have been regarded as proprietary systems, hard-wired to perform a limited set of logic operations. Controls suppliers started to offer PCs and general-purpose operating systems only five years ago. Still, none have reached the booming sales that experts predicted and none have offered open source code.

Control.com supported Linux because of its roots as an open, freely available system. Although the company plans to offer a soft PLC that incorporates the Linux-based control, it says that will not profit from the sale of the control code. "We plan to do what Red Hat does for Linux and offer support for it," said Ken Crater. "We'll also offer a hardware platform that it will run on."

The company will offer testing services at its lab, which will open in July. It will custom build PLC hardware for customers, much the way Dell Computer does for PC customers, Crater said. "What we always hear is that people don't go to open systems because of the lack of support. We're going to provide that," said Crater.

Control.com is a spin-off of Control Technology Corp. (Hopkinton, Mass.), a supplier of industrial control hardware. In a sense, however, it is also a product of the Automation List.

Complete frustration

Crater launched the idea for a Linux-based PLC after reading a Web-site posting from an automation engineer in mid-December 1999. "He posted a message expressing complete frustration at another of the abysmal, prolonged vendor-driven processes that result in a non-standard standard," Crater said. "When he suggested the Linux-based PLC, I immediately posted a reply saying we would put the support of our company behind it."

The message, written by consulting engineer Curt Wuollet of Wide Open Technologies (Onamia, Minn.), struck a cord among automation engineers who have grown tired of dealing with proprietary technologies. "I provided them with enough design information to let them know I was serious," said Wuollet. "People responded immediately. For awhile, I was getting 200-to-300 e-mails a day."

Wuollet's idea is to build a Linux-based foundation that could easily connect to Ethernet or to an industrial field bus and work with a system control and data acquisition system. "I want to do control and have access to the control code without having to license or pay royalties to anyone," Wuollet said.

Since announcing that Control.com would support development of such a PLC, Crater's Automation List has been deluged with postings that run the gamut from praise to cynicism. Some engineers are enamored with the idea. Approximately 150 A-List members from Europe, Asia and North America have volunteered to help develop the code. Others have questioned the company's motives. "I guess 'open' means 'open for business,' " wrote one site visitor.

Conventional PLC makers are unimpressed by the prospect. When asked about it, one referred to the Puffin PLC as a "science fair project."

Still, industry observers say that the concept has merit. "This system is not only open, it's free," Bullock said. "The big PLC makers will hate it."